Predictors of residual neoplasia after noncurative (R1) endoscopic submucosal dissection of lesions in the gastrointestinal tract.

BACKGROUND: Endoscopic submucosal dissection (ESD) is a minimally invasive resection technique that enables the en bloc resection of gastrointestinal lesions. Despite en bloc resection, pathological evaluation of lesions can reveal positive vertical or horizontal margins, which is referred to as R1 resection. Not all R1 lesions referred for surgical resection or endoscopic surveillance show evidence of residual tumor. We aimed to identify the predictors of residual neoplasia in patients with an R1 resection following ESD. PATIENTS AND METHODS: All lesions resected via ESD between June 2016 and September 2021 at a tertiary referral center were retrospectively identified. Lesions with an R1 resection and adequate follow-up were eligible for inclusion. Patient, lesion, and procedural characteristics were analyzed to identify predictors of residual neoplasia. RESULTS: Of 614 lesions, 163 (28%) had R1 resection. Of these, 56 lesions in 51 patients had complete follow-up and were included. Thirteen patients (25.5%) underwent surgical resection and the remainder underwent endoscopic surveillance. Seven (12.5%) patients had residual disease. All patients with residual disease had esophageal carcinoma. Positive deep and lateral margins, severe submucosal fibrosis, and moderate/poorly differentiated tumors were identified as significant predictors of residual neoplasia. CONCLUSION: Most R1 lesions (87.5%) resected by ESD did not have residual disease on follow-up. Those without identified risk factors for residual disease, such as esophageal carcinoma, severe submucosal fibrosis, or both histological margin positivity, may benefit from a strategy of close endoscopic surveillance rather than referral for surgical resection.

Hybrid Versus Conventional Colorectal Endoscopic Submucosal Dissection: A Multicenter Randomized Controlled Trial (Short-Endoscopic Submucosal Dissection).

INTRODUCTION: Hybrid endoscopic submucosal dissection (H-ESD), which utilizes ESD knife along with snare-based resection, has been developed to overcome the technical complexity of conventional ESD (C-ESD). The aim of this study was to compare the therapeutic outcomes of H-ESD vs C-ESD for nonpedunculated colorectal lesions ≥20 mm in size. METHODS: We conducted a multicenter randomized controlled trial to compare H-ESD and C-ESD (Short-ESD trial). Patients with colorectal lesions between 20 and 50 mm in size were randomly assigned (1:1) to H-ESD or C-ESD. Primary outcome was procedure time/speed. Secondary outcomes were en bloc and complete (R0) resection rates and adverse event rates. RESULTS: A total of 89 patients (median age 63 years; 49.3% women) with the median polyp size of 30 mm underwent H-ESD (n = 40) and C-ESD (n = 49). The mean procedure time of H-ESD was significantly shorter than that of C-ESD (41.1 ± 16.3 vs 54.3 ± 28.2 minutes; P = 0.007). The en bloc and R0 resection rates trended lower in the H-ESD vs C-ESD groups (77.5% vs 87.8%; P = 0.26% and 72.5% vs 79.6%; P = 0.46) without reaching statistical significance. Adverse event rate was similar between H-ESD and C-ESD (10% vs 8.2%; P = 1.00). DISCUSSION: Both H-ESD and C-ESD were safe and effective for resection of large colorectal lesions. H-ESD was associated with a shorter procedure time. H-ESD may represent a viable alternative to C-ESD, with the main advantage being easy applicability of a snare-based technique for colorectal lesions. Future studies are needed to further define the most suitable lesions for H-ESD, as to optimize efficiency and safety without compromising resection outcomes. ClinicaTrials.gov NCT NCT05347446.

A multicenter, retrospective study of a through-the-needle injection-capable electrosurgical knife for endoscopic submucosal dissection.

BACKGROUND AND AIMS: Endoscopic submucosal dissection (ESD) is a technically challenging resection technique for en-bloc removal of dysplastic and early cancerous gastrointestinal (GI) lesions. We conducted a single-arm retrospective study evaluating the safety and efficacy of a new through-the-needle injection-capable electrosurgical knife used in upper and lower ESD procedures performed at 6 US academic centers. METHODS: Data were retrospectively collected on consecutive cases in which the new ESD knife was used. The primary efficacy endpoint was successful ESD (en bloc resection with negative margins). Secondary efficacy endpoints included en-bloc resection rate, curative resection rate, median ESD time, and median dissection speed. The safety endpoint was device- or procedure-related serious adverse events (SAEs). RESULTS: ESD of 581 lesions in 579 patients were reviewed, including 187 (32.2%) upper GI and 394 (67.8%) lower GI lesions. Prior treatment was reported in 283 (48.9%) patients. Successful ESD was achieved in 477 (82.1% of 581) lesions ‒ lower for patients with versus without submucosal fibrosis (73.6% versus 87.0%, respectively, P < 0.001), but similar for those with versus without previous treatment (81.7% versus 82.3%, respectively, P = 0.848). Four hundred and forty-three (76.2% of 581) lesions met criteria for curative resection. Median ESD time was 1.0 (range 0.1-4.5) hour. Median dissection speed was 17.1 (IQR 5.3-29.8) cm2/hour. Related SAEs were reported in 15 (2.6%) patients, including delayed hemorrhage (1.9%), perforation (0.5%), or postpolypectomy syndrome (0.2%). CONCLUSION: A newly developed through-the-needle injection-capable ESD knife showed a good success rate and excellent safety at US centers. (ClinicalTrials.gov number, NCT04580940).

Outcomes of endoscopic submucosal dissection in cirrhotic patients: First American cohort.

BACKGROUND: Among patients with cirrhosis and pre-malignant or early malignant mucosal lesions, surgical intervention carries a much higher bleeding risk. When such lesions are discovered, endoscopic submucosal dissection (ESD) may offer curative therapy with lower risks than surgery and improved outcomes compared to traditional endoscopic resection. AIM: To evaluate the outcomes of ESD in patients with cirrhosis. METHODS: Patients with cirrhosis undergoing ESD between July 2015 and August 2022 were retrospectively matched in 1:2 fashion to controls based on lesion location, size, and anticoagulation use. Procedural outcomes were compared between groups. RESULTS: A total of 64 Lesions from 59 patients were included (16 cirrhosis, 43 control). There were no differences in patient or lesion characteristics between groups. En bloc and curative resection was achieved in 84.21%, 78.94% of the cirrhosis group and 88.89%, 68.89% of controls, respectively, with no significant differences. Cirrhotic patients had significantly higher rates of intra-procedural coagulation grasper use for control of bleeding (47.37% vs 20%; P = 0.02). There were otherwise no significant differences in adverse event rates. In the 29 patients with follow up, we found higher rates of recurrence in the cirrhosis group compared to controls (40% vs 5.26%; P = 0.019), however this effect did not persist on multivariable analysis controlling for known confounders. CONCLUSION: ESD may be safe and effective in patients with cirrhosis. Most procedure related outcomes were not significantly different between groups. Intra-procedural bleeding requiring use of the coagulation grasper use was expectedly higher in the cirrhosis group given the known effects of liver disease on hemostasis.

Development of clinical screening tool for exocrine pancreatic insufficiency in patients with definite chronic pancreatitis.

BACKGROUND/OBJECTIVES: No simple, accurate diagnostic tests exist for exocrine pancreatic insufficiency (EPI), and EPI remains underdiagnosed in chronic pancreatitis (CP). We sought to develop a digital screening tool to assist clinicians to predict EPI in patients with definite CP. METHODS: This was a retrospective case-control study of patients with definite CP with/without EPI. Overall, 49 candidate predictor variables were utilized to train a Classification and Regression Tree (CART) model to rank all predictors and select a parsimonious set of predictors for EPI status. Five-fold cross-validation was used to assess generalizability, and the full CART model was compared with 4 additional predictive models. EPI misclassification rate (mRate) served as primary endpoint metric. RESULTS: 274 patients with definite CP from 6 pancreatitis centers across the United States were included, of which 58 % had EPI based on predetermined criteria. The optimal CART decision tree included 10 variables. The mRate without/with 5-fold cross-validation of the CART was 0.153 (training error) and 0.314 (prediction error), and the area under the receiver operating characteristic curve was 0.889 and 0.682, respectively. Sensitivity and specificity without/with 5-fold cross-validation was 0.888/0.789 and 0.794/0.535, respectively. A trained second CART without pancreas imaging variables (n = 6), yielded 8 variables. Training error/prediction error was 0.190/0.351; sensitivity was 0.869/0.650, and specificity was 0.728/0.649, each without/with 5-fold cross-validation. CONCLUSION: We developed two CART models that were integrated into one digital screening tool to assess for EPI in patients with definite CP and with two to six input variables needed for predicting EPI status.

The use of a self-assembling peptide gel for stricture prevention in the esophagus after endoscopic submucosal dissection: a U.S. multicenter prospective study (with video).

BACKGROUND AND AIMS: Postoperative stricture is a serious common adverse event after extensive endoscopic submucosal dissection (ESD) in the esophagus. Self-assembling peptide (SAP) gel has been shown to promote tissue healing and re-epithelialization. The aim of this study was to evaluate the effect of the SAP gel for esophageal stricture prevention after ESD. METHODS: This was a multicenter prospective study of patients who underwent esophageal ESD followed by SAP gel application between March 2022 and December 2023. Patients were included if the ESD mucosal defect involved ≥50% of the circumference of the esophagus. High-risk cases were defined as mucosal defects ≥75% of the circumference. Stricture was defined as the inability to pass an endoscope ≥8.9 mm in diameter or a narrow-caliber lumen in a patient with symptoms. RESULTS: A total of 43 patients (median age, 71 years; 81.4% male) underwent ESD (median resected specimen size, 50 mm) during the study period. SAP gel (median, 3 mL) was successfully applied in all cases (median time, 4 minutes). In aggregate, stricture occurred in 20.9% (9 of 43) of the cases. Stricture developed in 30.8% of the high-risk cases: 80% (4 of 5) after circumferential ESD and 19% (4 of 21) in those with defects ≥75% but <100% of the circumference. All cases of stricture resolved with endoscopic treatment. Three cases (6.9%) of postoperative bleeding occurred and were adequately managed endoscopically. CONCLUSIONS: We show that SAP gel application was easy, quick, and associated with a relatively low stricture rate comparable to other prophylactic methods. Additional comparative studies are needed to corroborate these preliminary findings.

The role of transoral incisionless fundoplication (TIF) in the management of gastroesophageal reflux disease (GERD) following peroral endoscopic myotomy (POEM): A pilot, prospective, patient-driven study.

BACKGROUND: Gastroesophageal reflux (GERD) is a concern after peroral endoscopic myotomy (POEM). Transoral incisionless fundoplication (TIF) has been recently described as a possible therapy for post-POEM GERD in case series. METHODS: We prospectively enrolled patients undergoing POEM who agreed to participate in objective post-procedure GERD evaluation. Patients with objective evidence of GERD and suitable anatomy were offered TIF vs. proton pump inhibitor (PPI) only. Patients who underwent TIF were compared to those on PPI-only therapy after follow-up. RESULTS: Of 21 enrolled POEM patients with objective testing, GERD was found in 11 (52%). Of those eligible for TIF, 4 (40%) opted to pursue TIF and were compared to those on PPI-only therapy (n = 6). Three months post-TIF, 75% of patients had discontinued or significantly decreased PPI. There were no adverse events. GERD health-related quality of life scores were low and comparable between TIF (3.75 ± 6.2) and those who remained on PPI-only therapy (4.1 ± 5). CONCLUSION: In this pilot, patient-driven prospective study, 75% of patients with post-POEM GERD undergoing TIF had stopped or significantly reduced PPI use. Post-POEM TIF is safe and effective and may be a viable alternative to PPI for POEM-related GERD; however, future studies should include a control arm and post-intervention pH monitoring.

Efficacy and safety of endoscopic submucosal dissection for colorectal dysplasia in patients with inflammatory bowel disease: a systematic review and meta-analysis.

BACKGROUND/AIMS: In this meta-analysis, we studied the safety and efficacy of endoscopic submucosal dissection (ESD) for colorectal dysplasia in patients with inflammatory bowel disease (IBD). METHODS: Multiple databases were searched, and studies were retrieved based on pre-specified criteria until October 2022. The outcomes assessed were resection rates, procedural complications, local recurrence, metachronous tumors, and the need for surgery after ESD in IBD. Standard meta-analysis methods were followed using the random-effects model, and I2% was used to assess heterogeneity. RESULTS: Twelve studies comprising 291 dysplastic lesions in 274 patients were included with a median follow-up of 25 months. The pooled en-bloc resection, R0 resection, and curative resection rates were 92.5% (95% confidence interval [CI], 87.9%-95.4%; I2=0%), 81.5% (95% CI, 72.5%-88%; I2=43%), and 48.9% (95% CI, 32.1%-65.9%; I2=87%), respectively. The local recurrence rate was 3.9% (95% CI, 2%-7.5%; I2=0%). The pooled rates of bleeding and perforation were 7.7% (95% CI, 4.5%-13%; I2=10%) and 5.3% (95% CI, 3.1%-8.9%; I2=0%), respectively. The rates of metachronous recurrence and additional surgery following ESD were 10% (95% CI, 5.2%-18.2%; I2=55%) and 13% (95% CI, 8.5%-19.3%; I2=54%), respectively. CONCLUSIONS: ESD is safe and effective for the resection of dysplastic lesions in IBD with an excellent pooled rate of en-bloc and R0 resection.

Feasibility of peroral endoscopic myotomy with a disposable endoscope platform.

Video 1Demonstration of a successful peroral endoscopic myotomy using a novel disposable scope platform.

Ambulatory Endoscopic Submucosal Dissection for Gastrointestinal Neoplasms: Trends and Associated Factors in the United States.

Endoscopic submucosal dissection (ESD) is a minimally invasive treatment for superficial gastrointestinal (GI) cancers.1,2 ESD practice is expanding significantly in the United States and Western countries. This is attributed to a shorter hospital stay, better quality of life, and fewer adverse events compared with surgery. In the United States, ESD usually is performed and managed in an outpatient setting (ambulatory ESD) or with an overnight hospital stay. This practice is in contrast to Eastern Asian countries, where 3 to 5 days of hospital stay is a routine process for observation after ESD. A Swedish study showed that patients with well-selected colorectal neoplasms (median tumor size, 37 mm) could be managed safely in an outpatient setting after ESD.3 A North American multicenter ESD study also reported that ambulatory ESD was safe and feasible in selected cases (noninvasive cancers, no adverse events, high-volume endoscopists with short procedure time).4 However, procedural and technical aspects that enable safe outpatient management of patients after ESD need to be investigated.

Settings of a novel electrosurgical generator to enable efficient and safe submucosal endoscopic procedures.

Background and study aims A novel electrosurgical generator unit (ESU), ConMed Beamer, was recently introduced to facilitate endoscopic submucosal dissection (ESD) by employing Automatic Cutting Effect (ACE) technology. Its use in submucosal endoscopy has yet to be investigated. The aim of this study was to evaluate the feasibility and safety of performing ESD and peroral endoscopic myotomy (POEM) using novel settings generated with ConMed Beamer ESU. Patients and methods This was a single-center prospective study of 59 consecutive patients undergoing ESD/POEM at a tertiary referral center. ESU settings were initially generated by testing in live animal models prior to first in-human study. The primary outcome was technical success. Secondary outcomes were procedure times, rate of en bloc/R0 resection, and rate of adverse events (AEs). Results A total of 44 patients (50 polyps) and 15 patients underwent ESD and POEM, respectively. En bloc resection, R0 resection, and curative resection rates were 90%, 77.1%, and 70.8%, respectively. Mean maximal length of the lesion was 3.07 cm ± 1.43 with an average dissection speed of 14.2 cm 2 /hr ± 11.1. Technical success was achieved in 100% of POEM patients. Mean time (minutes) to complete the POEM procedure was 50.1 min ± 12.4. Two major AEs occurred among all patients (3.4%). All intraprocedural bleeding events were controlled using the ConMed Beamer ESU. Conclusions ConMed Beamer ESU settings generated from this study were proven safe and effective in a prospective cohort of patients who underwent submucosal endoscopic procedures. This novel ESU can be added to the armamentarium of ESD capable generators.

Response of Locally Advanced Pancreatic Cancer to Intratumoral Injection of Large Surface Area Microparticle Paclitaxel: Initial Report of Safety and Clinical Outcome.

OBJECTIVES: Large surface area microparticle paclitaxel (LSAM-PTX) provides an intratumoral (IT) chemotherapeutic depot. Safety, tolerability, and tumor response to IT LSAM-PTX delivered by endoscopic ultrasound-fine needle injection were evaluated in subjects with unresectable locally advanced pancreatic cancer (LAPC). METHODS: Ten subjects treated in a dose escalation phase and 22 additional subjects receiving 2 injections, 4 weeks apart, of 15 mg/mL LSAM-PTX were followed for 12 months. Paclitaxel pharmacokinetics were evaluated, imaging at 3 and 6 months determined tumor response, and multiplex immunofluorescence was conducted to characterize local immune response. RESULTS: Most treatment-emergent adverse events were attributed to LAPC. Plasma paclitaxel levels were negligible. Eight subjects' tumors became resectable after IT LSAM-PTX, and 5 of 6 (83%) were resected with R0. Multiplex immunofluorescence of resected tumors demonstrated increased T cells, natural killer cells, and macrophages and decreased myeloid-derived suppressor cells. Six-month disease control rate was 94%, and median overall survival was 19.7 months in the 2-injection subjects. For nonresected and resected groups, overall survival times were 18.9 and 35.2 months, respectively. CONCLUSIONS: Neoadjuvant IT LSAM-PTX, in combination with SOC, was well tolerated and may provide benefits to LAPC patients, evidenced by enhanced immune response, improved disease control rate, restaging leading to surgery, and extended survival.

Cold polypectomy techniques for small and diminutive colorectal polyps: a systematic review and network meta-analysis of randomized controlled trials.

OBJECTIVE: In the management of small and diminutive polyps, cold polypectomy is favored over electrocautery polypectomy. However, the optimal cold polypectomy technique is still controversial. Hence, this review aims to investigate the most effective cold technique for small and diminutive colorectal polyps. METHODS: We conducted a systematic review and network meta-analysis synthesizing randomized controlled trials (RCTs) which were retrieved by systematically searching PubMed, EMBASE, Web of Science, SCOPUS, and Cochrane through 10 February 2023. R software, (R version 4.2.0) and meta-insight software were used to pool dichotomous outcomes using risk ratio (RR) presented with the corresponding confidence interval (CI). Our protocol was prospectively published in PROSPERO with ID: CRD42022345619. RESULTS: Nineteen RCTs with 3649 patients and 4800 polyps were included in our analysis. Cold techniques (cold forceps polypectomy (CFP), jumbo forceps polypectomy (JFP), dedicated cold snare polypectomy (D-CSP), conventional cold snare polypectomy (C-CSP), underwater cold snare polypectomy (U-CSP), and cold snare endoscopic mucosal resection (CS-EMR) were included in our comparative analysis. CFP was less effective in achieving complete histological resection than C-CSP (RR: 1.10 with 95% CI [1.03-1.18]), CS-EMR (RR: 1.12 with 95% CI [1.02-1.23]), D-CSP (RR: 1.17 with 95% CI [1.04-1.32]), and U-CSP (RR: 1.21 with 95% CI [1.07-1.38]). However, the rest of the comparisons showed no difference. CONCLUSION: CFP is the least effective method for small and diminutive polyps' removal, and any snare polypectomy technique will achieve better results, warranting more large-scale RCTs to investigate the most effective snare polypectomy technique.

Safety and efficacy of underwater versus conventional endoscopic mucosal resection for colorectal polyps: Systematic review and meta-analysis of RCTs.

Background and study aims Conventional endoscopic mucosal resection (C-EMR) is limited by low en-bloc resection rates, especially for large (> 20 mm) lesions. Underwater EMR (U-EMR) has emerged as an alternative for colorectal polyps and is being shown to improve en-bloc resection rates. We conducted a systematic review and meta-analysis comparing the two techniques. Methods Multiple databases were searched through November 2022 for randomized controlled trials (RCTs) comparing outcomes of U-EMR and C-EMR for colorectal polyps. Meta-analysis was performed to determine pooled proportions and relative risks (RRs) of R0 and en-bloc resection, polyp recurrence, resection time, and adverse events. Results Seven RCTs with 1458 patients (U-EMR: 739, C-EMR: 719) were included. The pooled rate of en-bloc resection was significantly higher with U-EMR vs C-EMR, 70.17% (confidence interval [CI] 46.68-86.34) vs 58.14% (CI 31.59-80.68), respectively, RR 1.21 (CI 1.01-1.44). R0 resection rates were higher with U-EMR vs C-EMR, 58.1% (CI 29.75-81.9) vs 44.6% (CI 17.4-75.4), RR 1.25 (CI 0.99-1.6). For large polyps (> 20 mm), en-bloc resection rates were comparable between the two techniques, RR 1.24 (CI 0.83-1.84). Resection times were comparable between U-EMR and C-EMR, standardized mean difference -1.21 min (CI -2.57 to -0.16). Overall pooled rates of perforation, and immediate and delayed bleeding were comparable between U-EMR and C-EMR. Pooled rate of polyp recurrence at surveillance colonoscopy was significantly lower with U-EMR than with C-EMR, RR 0.62 (CI 0.41-0.94). Conclusions Colorectal U-EMR results in higher en-bloc resection and lower recurrence rates when compared to C-EMR. Both techniques have comparable resection times and safety profiles.

American Society for Gastrointestinal Endoscopy guideline on endoscopic submucosal dissection for the management of early esophageal and gastric cancers: methodology and review of evidence.

This document from the American Society for Gastrointestinal Endoscopy (ASGE) provides a full description of the methodology used in the review of the evidence used to inform the final guidance outlined in the accompanying Summary and Recommendations document regarding the role of endoscopic submucosal dissection (ESD) in the management of early esophageal and gastric cancers. This guideline used the Grading of Recommendations, Assessment, Development and Evaluation framework and specifically addresses the role of ESD versus EMR and/or surgery, where applicable, for the management of early esophageal squamous cell carcinoma (ESCC), esophageal adenocarcinoma (EAC), and gastric adenocarcinoma (GAC) and their corresponding precursor lesions. For ESCC, the ASGE suggests ESD over EMR for patients with early-stage, well-differentiated, nonulcerated cancer >15 mm, whereas in patients with similar lesions ≤15 mm, the ASGE suggests either ESD or EMR. The ASGE suggests against surgery for such patients with ESCC, whenever possible. For EAC, the ASGE suggests ESD over EMR for patients with early-stage, well-differentiated, nonulcerated cancer >20 mm, whereas in patients with similar lesions measuring ≤20 mm, the ASGE suggests either ESD or EMR. For GAC, the ASGE suggests ESD over EMR for patients with early-stage, well or moderately differentiated, nonulcerated intestinal type cancer measuring 20 to 30 mm, whereas for patients with similar lesions <20 mm, the ASGE suggests either ESD or EMR. The ASGE suggests against surgery for patients with such lesions measuring ≤30 mm, whereas for lesions that are poorly differentiated, regardless of size, the ASGE suggests surgical evaluation over endosic approaches.

American Society for Gastrointestinal Endoscopy guideline on endoscopic submucosal dissection for the management of early esophageal and gastric cancers: summary and recommendations.

This clinical practice guideline from the American Society for Gastrointestinal Endoscopy (ASGE) provides an evidence-based summary and recommendations regarding the role of endoscopic submucosal dissection (ESD) in the management of early esophageal and gastric cancers. It is accompanied by the document subtitled "Methodology and Review of Evidence," which provides a detailed account of the methodology used for the evidence review. This guideline was developed using the Grading of Recommendations, Assessment, Development and Evaluation framework and specifically addresses the role of ESD versus EMR and/or surgery, where applicable, for the management of early esophageal squamous cell carcinoma (ESCC), esophageal adenocarcinoma (EAC), and gastric adenocarcinoma (GAC) and their corresponding precursor lesions. For ESCC, the ASGE suggests ESD over EMR for patients with early-stage, well-differentiated, nonulcerated cancer >15 mm, whereas in patients with similar lesions ≤15 mm, the ASGE suggests either ESD or EMR. The ASGE suggests against surgery for such patients with ESCC, whenever possible. For EAC, the ASGE suggests ESD over EMR for patients with early-stage, well-differentiated, nonulcerated cancer >20 mm, whereas in patients with similar lesions measuring ≤20 mm, the ASGE suggests either ESD or EMR. For GAC, the ASGE suggests ESD over EMR for patients with early-stage, well- or moderately differentiated, nonulcerated intestinal type cancer measuring 20 to 30 mm, whereas for patients with similar lesions <20 mm, the ASGE suggests either ESD or EMR. The ASGE suggests against surgery for patients with such lesions measuring ≤30 mm, whereas for lesions that are poorly differentiated, regardless of size, we suggest surgical evaluation over endoscopic approaches.